This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 18 |
| 4 | 62 |
| 5 | 211 |
| 6 | 715 |
| 7 | 2420 |
| 8 | 8188 |
| 9 | 27701 |
| 10 | 93713 |
| 11 | 317030 |
| 12 | 1072506 |
| 13 | 3628263 |
| 14 | 12274327 |
| 15 | 41523752 |
| 16 | 140473848 |
| 17 | 475219625 |
| 18 | 1607656477 |
| 19 | 5438662906 |
| 20 | 18398864822 |
| 21 | 62242913851 |
| 22 | 210566269283 |
| 23 | 712340586524 |
| 24 | 2409830942708 |
| 25 | 8152399683933 |
| 26 | 27579370581033 |
| 27 | 93300342369742 |